Modern aircraft rely heavily on radio contact with ground based communication systems. In addition to conventional air traffic control communications, aircraft may use radio communication to upload weather information and provide telephone and data communication for passengers. In many aircraft one or more antennae are positioned below the aircraft to facilitate communication with ground based transmitters. In many instances such antennae are exposed to airborne water and contaminants as well as water and dust raised by the landing gear. Accordingly, antennae, cables, and couplers connecting the externally positioned antenna to internal cables are subject to deterioration due to corrosion and contamination.
Inefficient or defective performance of antennae, cables, and connectors is difficult to detect. In prior systems, a voltage standing wave ratio (VSWR) test function provided by the avionic radio enables evaluation of impedance differences between the internal circuits of the communications system and the antenna and cables. A result substantially above unity from the VSWR test function may result from a defect within the avionic radio or defective performance of the antenna, cables, or connectors. A non-unity results may prompt an operator to remove the radio for repair by a technician only to find that the radio is perfectly operable, while the antenna, cables, or connectors are defective. This process results in unnecessary interruption of aircraft service and wasted labor on the part of the repair technician.
In view of the foregoing it would be an advancement in the art to provide convenient systems methods for evaluating operability of a radio antenna and associated cabling without removing the communication system from the aircraft.